The UHF (Ultra High Frequency) radio band covers a range of frequencies between 300 MHz to 3 GHz. Radio frequencies within the UHF band have particularly useful propagation and information bearing properties therefore many systems which rely on the communication of information using radio waves are designed to transmit and receive information on radio signals using the UHF radio band.
To ensure a fair and organised allocation of the UHF spectrum, regulatory bodies, such as the Office of Communications (OFCOM) in the UK and the Federal Communications Commission (FCC) in the United States, divide the UHF spectrum into different frequency bands and allocate each band to a certain group of users and uses.
As time progresses, it becomes necessary for the regulatory bodies to re-organise the allocation of the UHF spectrum to accommodate new technologies which communicate using the UHF spectrum and to account for the demise of older technologies which no longer justify a reserved section of the spectrum. The task of reallocating bands of the UHF spectrum is not always made purely with technical considerations in mind.
For example, in the UK after 2012, radio transmitters broadcasting terrestrial television signals using the PAL (phase alternating line) analogue transmission mode on the so-called “800 MHz band” will cease transmitting. The “800 MHz band” refers to a range of frequencies between 790 MHz and 862 MHz. These frequencies will be re-allocated by OFCOM for other uses such as so-called “fourth generation” mobile communications services. As a result mobile devices (such as mobile telephones and other portable devices such as laptops, notebooks, camcorders, cameras with built in wireless communications functionality) can be expected to be deployed which transmit and receive radio signals on frequencies within the 800 MHz band. As fourth generation mobile devices become more widespread, this may cause interference problems with devices for receiving television signals such as televisions, personal video recorders (PVRs), set-top boxes and so on.